java Fork/join 初探

java7提供的forkJoinTask用多线程的方式处理可以用分治法解决的问题。

首先看一下forkJoinTask类的继承关系，在forkJoinTask中比较重要的两个类是RecursiveAction（没有返回值的线程父类）和RecursiveTask（有返回值的线程父类）。



在编写forkJoinTask类时要根据需要继承这两个类。编写完类后，创建ForkJoinPool这个线程池，实例化多线程对象，提交并启动多线程就可以了。

package com.Executor.test;

import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
import java.util.concurrent.TimeUnit;

public class ForkJoinPoolTest {
static class PrintTask extends RecursiveAction {
/**
*
*/
private static final long serialVersionUID = 1L;
private static final int THRESHOLD = 50;
private int start;
private int end;

public PrintTask(int start, int end) {
this.end = end;
this.start = start;
}

@Override
protected void compute() {
if (end - start < THRESHOLD) {
for (int i = start; i < end; i++) {
System.out.println(Thread.currentThread().getName() + " ::i=" + i);
}
} else {
int middle = (start + end) / 2;
PrintTask left = new PrintTask(start, middle);
PrintTask right = new PrintTask(middle, end);
left.fork();
right.fork();
}
}

}

public static void main(String[] args) throws InterruptedException {
System.out.println(Runtime.getRuntime().availableProcessors());
ForkJoinPool pool = new ForkJoinPool();
pool.submit(new PrintTask(0, 500));
pool.awaitTermination(2, TimeUnit.SECONDS);
pool.shutdown();
}

}

更详细的内容可以参考/article/8322814.html